The Universal Reset Module 422 is Designed to Operate All of The Mechanical Equipment in a Hydronic Heating System, Except For Zones, Coordinating Their Operation Through Network Communication. It Can be Used in Applications Ranging From a Single Zone of Baseboard With an On/Off Boiler to Multiple Fan Coils, Mixed Radiant Floor Zones, And a Modulating/Condensing Boiler. This Control Regulates up to Two Heating Water Temperatures Through Outdoor Temperature Reset And Indoor Temperature Feedback. It is Capable of Controlling a Single On/Off, Two Stage, or Modulating Boiler, a Mixing Device, Domestic Hot Water, Setpoint Loads, And Can Expand up to 24 Zones in Total For Each Heating Water Temperature. For Further Information And up to Date Literature Visit: Tekmar Documentation | Tekmar Controls | 422